Implantable biodegradable wound closure device

ABSTRACT

A biodegradable device for maintaining the alignment of the edges of a trocar defect, consisting of two bases joined by a connector, a first base to be positioned below the defect and a second base above. The first base has a threaded hole from its upper surface but not through the lower surface. The connector attached to the bases such that there is a hole aligned with the threaded hole in the first base allowing a device to mate with the threads in the first base. The second base has a hole aligned with the hole in the connector and wide enough to allow a device to mate with the threads in the first base. The device is arranged so the distance between the lower surface of the second base and upper surface of the first base holds but does not compress the fascia around the trocar defect.

This patent is a divisional of “An Implantable Biodegradable WoundClosure Device and Method”, filed on Apr. 11, 2010 as U.S. applicationSer. No. 12/758,027.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention generally relates to a wound closure device thatis used to repair the defect typically left in the fascia layer duringlaparoscopic surgery by an instrument called a trocar.

Laparoscopic surgery was introduced as an alternative to open surgicalmethods. Also referred to as minimally invasive surgery, the techniqueallows for small incision access to the intra-abdominal cavity. Theapproach utilizes specialized equipment for the purposes of inflatingthe abdominal cavity with gas, deploying and exchanging instrumentsduring the operation, and real time imaging with a videoscopic camera.

A laparoscopic trocar is a surgical device used for laparoscopicprocedures to pierce and access the wall of an anatomical cavity,thereby forming a passageway providing communication with the inside ofthe cavity. Other medical instruments such as videoscopes and operatinginstruments can thereafter be inserted through the passageway to performvarious medical procedures within the anatomical cavity.

When the procedures are over, the laparoscopic trocar is removed,leaving a residual defect in the fascia-peritoneal layer. Laparoscopictrocars are typically 5-15 mm in diameter. Generally, any port sizelarger than 5 mm should be closed because of the risk of hernias. Thedefect is located deep in the abdominal wall, making it difficult toview.

Trocar site herniation is a recognized complication of laparoscopicsurgery. Omental, and sometimes intestinal, herniation withincarceration and obstruction has been documented in recent surgicalliterature, occurring particularly at any trocar insertion site largerthan 5 mm that was not sutured at operation. The necessity to performfascial closure of any trocar insertion site larger than 5 mm has nowbeen established and is routinely practiced worldwide.

However, the conventional closure of such a trocar site fascial defectis often technically difficult, frustrating, indefinitely successful,and even sometimes dangerous due to the limited size of skin incision,the depth of the subcutaneous fatty layer, and necessity of blindmanipulation. Moreover, the suturing that involves placement of deepblind sutures after the abdomen has been decompressed is a dangerousmanipulation that surgeons tend to avoid.

A number of techniques and instruments have been suggested to facilitatea safe and secure closure of the fascial defect through the tiny skinopening. Many of these repairs include passing in any way a suture fromone side of the trocar wound to the other, and its ligation. For thispurpose either a heavy needle or a variety of straight needles throughwhich sutures are passed have been used. Problems arise as both sides ofthe defect may not be sutured. Also, in overweight and obese patientswith thick abdominal walls, reliable fascia closure is very difficult toachieve. This results in a delayed hernia formation such as anincarcerated or symptomic hernia. The literature shows as much as a 6%overall hernia complication rate, resulting in reoperation,rehospitalization, and extended disability. In the best case thisresults in the need for an elective repair, resulting inrehospitalization.

Although as easy and quick methods, these suturing techniques requirepositioning of the camera and graspers, visualization of the needlesduring their entrance into the peritoneal cavity, feeding of thegraspers or suture passers with the suture loop, all of which arerepeated once to thrice for every trocar defect. Any of these suturingtechniques are not only time and effort consuming, but also requiresophisticated laparoscopic talent and coordination. As more defects atvarious sites in the abdominal wall are to be closed after advancedlaparoscopic operations, the laparoscopic procedures that support thesuturing techniques become more complicated and complex. Theabove-mentioned suturing techniques would therefore be not that easy andquick.

Techniques using such instruments as the Carter-Thomason or Riza-Ribe®needles work by adding a catch onto the end of a needle assembly tocatch a free floating suture. To facilitate the closure of the fasciadefects of a trocar entry site greater than 5 mm, the surgeon places theupper end of a dissecting forceps through the fascial defect and tiltsit so that the peritoneum comes into contact with its flat surface. Anassistant retracts the skin and subcutaneous tissue and the needle withthe appropriate suture material is then used to take a stitch throughthe fascia under direct vision. The sharp end of the needle is preventedfrom coming into contact with any deeper structure as it slides on theflat surface of the dissecting forceps. The stitch is then pulled up tolift the edge of the fascia and the needle is passed from the oppositeedge of the fascia in the same manner and then the suture is ligated.

Moreover, a series of manipulations is needed to complete a singlesuturing. The conventional suturing technique involves much traumaticmanipulation including pushing, pulling and retraction of the wound, andinsertion and extraction of needles. Most of the time the needle ispassed twice, and sometimes more (as depicted in Petrakis' technique).As manipulation in the wound increases, the inflammation and risk ofensuing infection rise considerably. The edema and the collection ofseroma and hematoma at the wound further cause dehiscence and herniaformation on a long-term basis.

Excessive traumatic manipulation and suturing with heavy sutures opposethe “minimal damage” basis of laparoscopic surgery. The patients aresubject to pain and complications at their trocar sites in thepostoperative period. The problems associated with the repair of trocarwound would be annoying to the patient as he (or she) is discharged onthe first or second postoperative day. The problems of the wound wouldcause the patient to refer back to the institution.

Any of these suturing techniques are to be done under direct vision. Itis however impossible to repair the last trocar wound under directvision. Unless a 0.5 cm scope is used, the last large trocar site canonly be closed with conventional blind sutures. This is because at theconclusion of a typical multiport laproscopy procedure, all the portsare removed simultaneously and positive intra-abdominal pressure is lostimmediately. The abdominal wall returns to a flat configuration, and the10-12 mm trocar port incisions are then individually dosed. Therefore,there is no visibility on the surgeon's part. For a regular laparoscopiccholecystectomy, the surgeon can only repair the first of two largetrocar defects under direct vision, and only then if he usesintracorporeal suturing, which is rarely performed because of the levelsof skill and expertise required. In any case, he must close the last oneblindly.

No matter which suturing technique or needle is used, it is not possibleto eliminate the trocar site hernias completely. As described inMalazgirt (US patent application, pub #20060015142 published Jan. 19,2006), the current incidence is reportedly between 0.77-3%. As complexLaparoscopic surgery becomes more common, the incidence of thiscomplication increases. The reported rates of hernia show that there isnot yet any superior method in the safe closure of the trocar fascialdefect.

Eldridge and Titone (U.S. Pat. No. 6,120,539 Issued Sep. 19, 2000)proposed a prosthetic repair fabric constructed from a combination ofnon-absorbable tissue-infiltratable fabric which faces the anteriorsurface of the fascia and an adhesion-resistant barrier which facesoutward from the fascia. This prosthetic requires the use of sutures tohold it in place.

Eberbach (U.S. Pat. No. 5,366,460 Issued Nov. 22, 1994) proposed the useof a non-biodegradable fabric-coated loop inserted through the defectinto the fascia wall, pressing against the posterior fascia wall fromthe intra-abdominal pressure.

Agarwal et al (U.S. Pat. No. 6,241,768 Issued Jun. 5, 2001) proposed aprosthetic device made of a biocompatible non-biodegradable mesh, whichsits across the fascia defect using the abdominal pressure to hold it inplace.

Rousseau (Pat Pub#20030181988) proposed a plug made of biocompatiblenon-biodegradable material which covers the anterior side of the fascia,the defect, as well as the posterior side of the fascia.

Malazgirt (Pat Pub#20060015142) proposed a plug/mesh non-biodegradablecombination for repair of large trocar wounds. It is stated that itrequires at least a “clean flat area around with a radius of 2.5 cm”,and requires staples to hold it in place.

Ford and Torres (Pat Pub#20060282105) proposed a patch with a tether orstrap, all made of non-biodegradable biocompatible material placedagainst the anterior wall of the fascia defect.

SUMMARY

A biodegradable device for maintaining the alignment of the edges of atrocar defect, consisting of two bases joined by a connector, a firstbase to be positioned below the defect and a second base above. Thefirst base has a threaded hole from its upper surface but not throughthe lower surface. The connector attached to the bases such that thereis a hole aligned with the threaded hole in the first base allowing adevice to mate with the threads in the first base. The second base has ahole aligned with the hole in the connector and wide enough to allow adevice to mate with the threads in the first base. The device isarranged so the distance between the lower surface of the second baseand upper surface of the first base holds but does not compress thefascia around the trocar defect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a transparent view of the device at the end of thecompression process in accordance with one or more embodiments of thepresent invention.

FIG. 2 shows a transparent view of the device for closing a wound inaccordance with one embodiment of the present invention.

FIG. 3 shows a view of the disassembled parts in accordance with one ormore embodiments of the present invention.

FIG. 4 shows a cross-section of an embodiment of the wound closuredevice.

FIG. 5 shows a detailed bottom view of the subfascial button inaccordance with one or more embodiments of the present invention.

FIG. 6 shows a detailed top view of the superfascial button along withits attached screw in accordance with one or more embodiments of thepresent invention.

FIG. 7 shows a view of the top of the superfascial button in accordancewith one or more embodiments of the invention.

FIG. 8 shows a view of the bottom of the superfascial button and screwassembly for one or more embodiments of the current invention.

FIG. 9 shows a detailed view of the central insertion stem in accordancewith one or more embodiments of the present invention.

FIG. 10 shows a detailed view of the hollow tube component in accordancewith one or more embodiments of the present invention.

FIG. 11 shows a view of the device in accordance with one or moreembodiments of the current invention.

FIG. 12 shows a view of an embodiment of the wound closure device whenit is being compressed into the wound.

FIG. 13 shows a view of an embodiment of the device being insertedthrough the tunnel.

FIG. 14 shows a view of an embodiment of the device in place.

FIG. 15 shows a view of an embodiment of the device during the healingprocess.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a transparent view of an embodiment of the insertion tool,compression tool, and the wound closure device. The wound closure deviceconsists of a subfascial button 102, screw 110, and superfascial button104. In one or more embodiments, the insertion tool consists of acentral insertion stem 108. In one or more embodiments, the compressiontool consists of an outer tube 106.

In one or more embodiments, the superfascial button 104 is permanentlyattached to the screw 110. The screw 110 gets inserted into a threadedhole in the subfascial button 102. These three components make up whatis referred to as the “wound closure device”. The central insertion stem108 screws into a threaded hole in the base of the subfascial button102. The central insertion stem 108 is used by someone on the surgicalteam to guide the wound closure device into the wound. The hollow tube106 slips over the central insertion stem 108 onto a connector on top ofthe superfascial button 104 can then be used to tighten the woundclosure device onto the fascia around the wound. In one or moreembodiments, the central insertion stem 108 is longer than the hollowtube 106, sufficiently longer so that the hollow tube 106 can be held byone person at the same time that another person (or the same person inthe other hand) is holding the central insertion stem 108. Once thewound closure device is tightened, the central insertion stem 108 andhollow tube 106 can be removed.

FIG. 2 shows a direct side-on hidden line view of an embodiment of thewound closure device, compression tool, and insertion tool. Thesubfascial button 102 is shown in position after compression against thesuperfascial button 104, with the hollow tube 108 and central insertionstem 108 still attached. The screw 110 attached to the superfascialbutton 104 is shown screwed into the subfascial button 102.

FIG. 3 shows a view of each of the parts disassembled. The subfascialbutton 102 will be attached to the superfascial button 104 via the screw110. In one or more embodiments the screw is permanently attached to thesuperfascial button 104. The screw 110 and superfascial button 104 havea central hole large enough for the central insertion stem 108 to slidethrough so that it can be attached to the base of the subfascial button102. Connecting the central insertion stem 108 to the base of thesubfascial button 102 provides stability to the device during insertion.In one or more embodiments, the threads holding the central insertionstem 108 to the base of the subfascial button 102 are of an oppositehandedness to the threads holding the screw 110 to the base of thesubfascial button 102. This means that tightening one will not loosenthe other.

FIG. 4 shows a cross-sectional view of the assembly. The face 420 of thesubfascial button 102 has one or more protrusions 414 attached. The face420 of the subfascial button is of a smaller diameter than the cupped402 portion of the superfascial button 104, such that the protrusions414 of the subfascial button 102 fit inside the cupped portion 402 ofthe superfascial button 104. The central insertion stem 108 fits intothreads in the subfascial button 412 which extend from the threads inthe subfascial button for the screw 410.

Subfascial Button

FIG. 5 shows a view of the subfascial button as it is in one or moreembodiments. The subfascial button 102 consists of a cone 508 and a base506. The base 506 is of roughly constant diameter. In one or moreembodiments, the cone 508 allows the wound closure device to pushthrough the wound easier. The subfascial button has a hole with screwthreads 502 substantially through the center of the face 504 extendingthrough the base 506 and into the cone portion 508, such that the screwthreads 502 are deep enough to stably connect the subfascial button 102to the screw. The diameter of the subfascial button 102 at the end ofthe screw threads is such that neither reasonably sufficient torque onthe screw to tighten it into the subfascial button 102 nor the act ofpushing the subfascial button cone 508 through the fascia would causethe subfascial button 102 to crack. Not shown in the figure but clearlyshown in other figures is a smaller hole deeper into the cone 412 thanthe hole for the screw 502. This hole is also substantially through thecenter, has threads of a handedness and diameter that it can connectwith the central insertion stem 108.

In one or more embodiments, the subfascial button base 506 has a thin,flat profile of a few millimeters in thickness, is moderately rigid instructure and circular or elliptical in shape. This profile is desirableto lessen the likelihood of the patient's awareness of its presence ordiscomfort during the post-operative healing interval.

In one or more embodiments, a counter-rotational or frictional controlfeature can be added to the subfascial button face 504 such as smallprotrusions 414 of a conical shape to prevent the tendency to rotateduring the process of tightening the superfascial button 104 onto theanterior surface of the fascia. In one or more embodiments, thisfrictional control feature is implemented where the face of thesubfascial button 504 is textured with a patterned surface to offerfrictional control such that, in use, the textured side is placed indirect contact with the fascia and associated layers of the abdominalwall, and covers the trocar defect. Its purpose is to align the edges ofthe linear defect and hold them in place to facilitate the healingprocess. In one or more embodiments, the texture is a non-smooth(unpolished) frictional control surface feature to assure that thesubfascial button 102 remains in position and does not slide or shiftlaterally during the healing interval.

As deployed and implanted, the subfascial button 102 is located underthe fascial defect and is a mating member of the wound closure device.Like the superfacial button 104, its goal is to close and securely alignthe trocar port defect in the fascia, and hold it in place for theintended healing interval. And, similarly, its purpose is fulfilled andcompleted at the end of the intended healing interval when the woundclosure device should dissolve.

The Screw

The screw 110 is of such length so that it can be inserted into thesubfascial button 102 and still has sufficient length to straddle thefascia. In one or more embodiments, it must also be of large enoughdiameter to enable the central insertion stem 108 to be inserted throughthe screw into the finer threads of the subfascial button. In one ormore embodiments, the length of the screw 110 can be made at varyinglengths to enable use for patients with differing tissue thicknesses andminimize the exposure of the screw 110. In one or more embodiments, thescrew 110 is permanently attached to the bottom of the superfascialbutton 104. In other embodiments, the screw 110 is independent of thesubfascial button and superfascial button 104, and so the length of thescrew 110 must be taken into account to minimize the length of the screw110 present beyond the superfascial button 104.

In one or more embodiments, the diameter of the screw 110 may be made atvarying widths to support the closure of different diameter wounds. Inone or more embodiment, the screw 110 has a hole through its centerwhich accepts the central insertion stem 108. In one or moreembodiments, where the screw 110 is not permanently attached to thesuperfascial button 104, to prevent loosening, the threads between thescrew 110, superfascial button 104 and subfascial button 102 are adifferent hand-sense (i.e. right-handed vs. left-handed) than thethreads between the subfascial button 102 and central insertion stem108.

In one or more embodiments, the screw 110 can be permanently connectedto either the subfascial button 102.

In one or more embodiments, the screw 110 may be replaced by a lockingor clasping mechanism. This locking or clasping mechanism can beconfigured with frictional features or ratcheting and interlockingprotrusions to secure the subfascial button base 420 and superfascialbutton base 418 components together, and hold them with the desireddegree of tension across the fascia and associated layers.

Superfascial Button

As shown in FIG. 6, the superfascial button 104 consists of a base 606and a connector 602, the base 606 being closer to the fascia. Thesuperfascial button 104 has a hole through the center 604 which allowsthe central insertion stem 108 to be slipped through it. In one or moreembodiments, the connector 602 consists of one or more grooves that aredeep enough so that a compression tool with protrusions could beinserted into the grooves. The compression tool would have enoughcontact between the protrusions and the grooves such that torque can beapplied by the tool to tighten the superfascial button 104 onto thesubfascial button 102.

As shown in FIG. 7, in one or more embodiments, the connector may beembodied as a raised ring 704 with two or more notches 706 in the ring.These notches 1006 are in a pattern that matches the pattern ofprotrusions attached to the end of an embodiment of a compression tool.The notches 706 are of enough width to accommodate the protrusions. Aswith other embodiments, this embodiment would also have a screw attached702 and a hole 708 to allow the central insertion stem 108 to slipthrough it.

An embodiment of the superfascial button 104 is shown in FIG. 8. In oneor more embodiments, the superfascial button base 804 has a thin, flatprofile of a few millimeters in thickness, is moderately rigid instructure and circular or elliptical in shape. This profile is desirableto lessen the likelihood of the patient's awareness of its presence ordiscomfort during the post-operative healing interval. In one or moreembodiments, the base would have sides which curve upward at the edges802. The sides should be high enough above the flat profile so thatfascia and associated layers are engaged between the inner wall of theside and the edge of the subfascial button. By doing so, the sidesencourage the device to remain at the location of wound, furtherassuring the anatomical alignment of the wound edges, and countering thetendency of the fascia and associated layers to pull away.

In one or more embodiments, the screw 110 is permanently attached to thebase 806. There is a hole in the screw 808 that is aligned with the holethrough the superfascial button 604. The hole is of such size and shapeto allow the central insertion stem 108 to slip through it.

In one or more embodiments, the superfascial button base 606 has a thin,flat profile of a few millimeters in thickness, is moderately rigid instructure and circular or elliptical in shape. This profile is desirableto lessen the likelihood of the patient's awareness of its presence ordiscomfort during the post-operative healing interval.

General Composition of the Wound Closure Device

Materials specified for the wound closure device are specific for itsintended application and use. The scope of materials that will satisfythe requirements of this application is unusually narrow. This is adirect consequence of the specificity and functional demandscharacteristic of the intended surgical application.

The intention for the wound closure device is to close and secure thetrocar port defect in the fascia. This requires a known and finitehealing interval of some three to five months. Its purpose fulfilled atthe end of this period, making continued presence of the closure devicea potential liability. To prevent it from becoming a source forirritation once the healing process is completed, the implanted closuredevice should be removed. Consequently, to avoid the need for a secondsurgical intervention to remove the device, Maurus and Kaeding (Maurus,P. B. and Kaeding, C. C., “Bioabsorbable Implant Material Review”, Oper.Tech. Sports Med 12, 158-160, 2004) found it was a primary requirementfor the wound closure device is that it is biodegradable. This meansthat the materials will degrade or disintegrate, being absorbed in thesurrounding tissue in the environment of the human body, after adefinite, predictable and desired period of time. One advantage of suchmaterials over non-degradable or essentially stable materials is thatafter the interval for which they are applied (i.e. healing time) haselapsed, they are no longer a contributing asset and do not needsubsequent surgical intervention for removal, as would be required formaterials more stable and permanent. This is most significant as itminimizes risks associated with repeat surgeries and the additionaltrauma associated with these procedures.

A disadvantage of these types of materials is that their biodegradablecharacteristic makes them susceptible to degradation under normalambient conditions. There is usually sufficient moisture or humidity inthe atmosphere to initiate their degradation even upon relatively briefexposure. This means that precautions must be taken throughout theirprocessing and fabrication into useful forms, and in their storage andhandling, to avoid moisture absorption. This is not a serious limitationas many materials require handling in controlled atmosphere chambers andsealed packaging; but it is essential that such precautions areobserved. Middleton and Tipton (Middleton, J. and Tipton A. “SyntheticBiodegradable Polymers As Medical Devices” Medical Plastics andBiomaterials Magazine, March 1998) found that this characteristic alsodictates that their sterilization before surgical use cannot be doneusing autoclaves, but alternative approaches must be employed (e.g.exposure to atmospheres of ethylene oxide or gamma radiation with cobalt60).

While biodegradability is an essential material characteristic for thewound closure device, the intended application is such that a furtherrequirement is that the material is formulated and manufactured withsufficient compositional and process control to provide a preciselypredictable and reliable degree of biodegradability. This means atypical biodegradation interval of three to five months, correspondingto the healing interval for the trocar defect in the fascia layer.

In these materials, simple chemical hydrolysis of the hydrolyticallyunstable backbone of the polymer is the prevailing mechanism for itsdegradation. As discussed in Middleton and Tipton (Middleton, J. andTipton A referenced previously), this type of degradation when the rateat which water penetrates the material exceeds that at which the polymeris converted into water-soluble materials is known as bulk erosion.

Biodegradable polymers may be either natural or synthetic. In general,synthetic polymers offer more advantages than natural materials in thattheir compositions can be more readily finely-tuned to provide a widerrange of properties and better lot-to-lot uniformity and, accordingly,offer more general reliability and predictability and are the preferredsource.

Synthetic absorbable materials have been fabricated primarily from threepolymers: polyglycolic acid (PGA), polylactic acid (PLA) andpolydioxanone (PDS). These are alpha polyesters or poly (alpha-hydroxy)acids. The dominant ones are PLA and PGA and have been studied forseveral decades. Gilding and Reed (Gilding, D. K and Reed A. M.,“Biodegradable Polymers for Use in Surgery” Polymer 20, 1459-1464)discussed how each of these materials has distinctive, uniqueproperties. One of the key advantages of these polymers is that theyfacilitate the growth of blood vessels and cells in the polymer matrixas it degrades, so that the polymer is slowly replaced by living tissueas the polymer degrades (“Plastic That Comes Alive: Biodegradableplastic scaffolds support living cells in three dimensional matrices sothey can grow together into tissues and even whole organs” by Cat FaberStrange Horizonshttp://www.strangehorizons.com/2001/20010305/plastic.shtml)

In recent years, researchers have found it desirable for obtainingspecific desirable properties to prepare blends of these two dominanttypes, resulting in a highly useful form, or co-polymer, designated asPLGA or poly (lactic-co-glycolic acid). Asete and Sabilov (Asete, C. E.and Sabilov C. M., “Synthesis and Characterization of PLGANanoparticles”, Journal of Biomaterials Science—Polymer Edition 17(3)247-289 (2006)) discuss how this form is currently used in a host ofFDA-approved therapeutic devices owing to its biodegradability andbiocompatibility.

In one or more embodiments, the biodegradable wound closure device maybe made of biodegradable material of different stability (i.e.half-life). While it is important for the material that is in directcontact with the fascia or lending support to that (the subfascialbutton base 506, screw 110, and superfascial button base 606) needs tostay in place for a few months, while the rest of the implantablestructure can degrade significantly in a matter of weeks withoutaffecting the performance of the payload. In one or more embodiments,the screw 110 would degrade sooner than the subfascial button base 506and superfascial button base 606, so that the ends of the defect areallowed to grow together while protecting the surface of the defect.

Material for the Subfascial Button

Owing to its necessarily and virtually inaccessible location beneath thefascia and peritoneum and its need to be placed and positioned correctlyand precisely in proper alignment with the superfascial button base 606located on the other side, the material used for the subfascial buttonbase 506 must be even more specialized than the superfascial button base606. That is, besides the same requirement for biodegradability andbiocompatibility, the additional need for its placement and positioningin a virtually inaccessible and invisible location imposes much morestringent specifications and limitations upon the grade of polymer usedfor this component.

In one or more embodiments, the subfascial button 102 is made from shapememory biodegradable polymer, such that the cross-section of itsinsertion is small, but over time it expands against the fascia. In oneembodiment, it would be inserted in a teardrop shape, and once in placeexpand into a flattened disc-like shape.

Although various pre-insertion bending and folding manipulativeprocedures might be conceived and envisioned for controlling the profileof the subfascial button base 506 to enable it to be inserted into andthrough the subcutaneous tissue and fascial defect and then, somehow,unfolded and flattened, and deployed into its desired position correctlyaligned with the superfascial button 104; such requirements areconsidered essentially unreliable, excessively time-consuming and ofseriously doubtful feasibility for a practical and increasingly commonsurgical procedure. For these reasons, in one or more embodiments of theinvention, the material contemplated for the subfascial button base 506is a co-polymer having the desired biodegradability characteristics forthe application, but also one that possesses a shape-memory property.Shape memory polymers are discussed in Lendlein and Kelch (Lendlein, A.and Kelch, J. “Shape-Memory Polymers” Angewandte Chem. Int. Ed., 41,2034-2057 (2002)) and described further in Kawai and Matsuda (U.S. Pat.No. 4,950,258, issued Aug. 21, 1990).

Polymer systems with shape-memory properties have an attractive andbroad application potential in minimally invasive (e.g. laparoscopic)surgery, the field of interest for this invention. Absorbable implantsof the material can be inserted into the human body in a compressed ordeformed (temporary) shape through a small incision (as the trocarfascial defect of this disclosure). After being placed into the desiredposition, (Kawai and Matsuda (U.S. Pat. No. 4,950,258, issued Aug. 21,1990) described how shape memory polymers can be reverted back to theirdesired final functional shape upon warming to body temperature.

During the appropriate healing interval, the implant is degraded andabsorbed, making subsequent surgery to remove the implant unnecessary.These shape-memory materials may be suitably modified to achieve theprecisely desired behavior for specific applications.

For biomedical applications such as the wound closure device, a thermaltransition of the shape of the shape-memory material in a fairly narrowtemperature range between room (ambient) and body temperature isdesired. Such materials have been developed and are available forapplication in the present contemplated invention. Nevertheless, becauseof the demanding nature of this application and the need for rigidlynarrow operating temperature limits, as well as assurance of adequatemechanical properties, it is expected and probably unavoidably necessarythat some co-polymer development will be required to achieve an optimalbalance of properties for this very specific application.

In use, and having an implantable subfascial button 102 of the desiredgeometry of optimal material, the circular or elliptically shaped discwould be deformed such that its deformed profile would be readilyinsertable into and through the subcutaneous tissue layer and trocarfascial defect. This maneuver would desirably take place within a brieftime interval to assure that the polymeric material did not reach itsshape-memory transition temperature (i.e. body temperature) before beingpositioned into its required and desired location behind or under thefascial defect.

Material for the Superfascial Button

Depending upon the ratio of lactide-to-glycolide used forpolymerization, different forms or grades of PLGA are obtainable. Theseare usually identified according to the monomers' ratio and are sodesignated in the literature and suppliers' brochures. PLGA has beensuccessful as a biodegradable polymer for medical applications becauseit undergoes hydrolysis in the body to produce the original monomers,lactic acid and glycolic acid.

The two monomers associated with PLGA, lactide and glycolide, undernormal physiological conditions, are byproducts of various metabolicpathways in the human body. Since the body effectively deals with thesetwo monomers, there is minimal system toxicity associated with use ofthis co-polymer. A notable feature of PLGA is that it is possible totailor the polymer degradation interval by adjusting the ratio ofmonomers. In light of the versatility of the PLGA co-polymer and itsrecord of successful use in a wide range of bio-absorbable applications,it is the specified material for the superfascial button base 606.

Insertion Tool

In one or more embodiments, the insertion and the minimal positioningexpected to be required would be accommodated with an attachedpositioning stem fastened to the subfascial button 102. The insertiontool consists of an insertion mechanism to place the wound closuredevice into position at the fascia defect. In one or more embodiments,the insertion mechanism is a central insertion stem 108, as describedbelow.

Central Insertion Stem

The central insertion stem enables the wound closure device to beinserted through the trocar tunnel (subcutaneous tissue layer) andfascial defect and placed below the fascia. As shown in FIG. 9, thecentral insertion stem 108 is a solid piece of cylindrical materialwhich is threaded at the lower end. These threads 904 are of sufficientlength to attach to the biodegradable wound closure device into thescrew to hold the biodegradable wound closure device steady throughoutan insertion procedure. The stem handle 902 must be of significantlength to be grasped while simultaneously grasping the outer tube body.In one or more embodiments, the diameter of the central insertion stem108 used in a particular procedure may vary to support different woundsizes.

The central insertion stem 108 would extend up and out in a forwardanterior direction through the fascia defect and be manuallymanipulatable by the surgeon. At this point, with the subfascial buttonin its proper position under the fascia defect, it can be brought upagainst the peritoneum and underside of the fascia by the surgeon simplyexerting an upward (outward) manual force upon the central insertionstem.

In one or more embodiments, a frictional or ratcheting holding featureis provided between a hole in the superfascial button and the lowersurface of the central insertion stem whereby the superfascial buttonbecomes secured to the central insertion stem, allowing the subfascialbutton base 506 and superfascial button base 606 to sandwich the fasciaand associated layers between them. This feature is designed to allowthe desired degree of compressive force to be maintained without furtherapplication of continual external manual pressure. At this point in theclosure device implant procedure the closure device is self-sustaining,independent of the need for external force and in its desired position.

Outer Tube

As shown in FIG. 10, the outer tube 106 is a hollow tube that fits overthe central insertion stem 108 at one end and into the connector of thesuperfascial button 602 at the other. The outer tube 106 has a body 1010that is of significant length to enable one to grasp it comfortably fromoutside the body, and one or more protrusions 1006 which enable theouter tube 106 to detachably connect to the connector 602. The innerdiameter of the outer tube 106 should be significantly greater than thediameter of the central insertion stem 108. In one or more embodiments,the outer diameter of the outer tube 106 must be smaller than thediameter of the superfascial button 104 to allow the outer tube 106 tosit on top of the superfascial button 104. In other embodiments, theouter tube 106 may be wider than the superfascial button 104 such thatthe protrusions 1006 on the bottom of the outer tube can be insertedinto the grooves 602 on the superfascial button 104.

In one or more embodiments, the face of the outer tube 1004 issurrounded by a curved edge 1002 in such a way so that it substantiallycovers the head of the superfascial button, improving the stability ofthe connection between the outer tube and superfascial button.

Once the wound closure device has been put into place by the centralinsertion stem 108, the outer tube 106 would be introduced to allow thesurgeon to assure mutual seating of both the subfascial button 102 andsuperfascial button 104 tightly against either side of the fascia. Thiswould simply require application of an upward manual force to thecentral insertion stem (attached to the subfascial button) andsimultaneously-applied downward pressure to the hollow tube 106contacting the superfascial button 104. Such opposing manual forceswould readily bring the superfascial button 104 and subfascial button102 together with the fascia sandwiched in between. In one or moreembodiments, this downward force on the hollow tube 106 would alsorequire a torque force to turn the superfascial button 104 so that itmoves closer to the subfascial button.

The wound closure device only comes into play toward the end of thesurgical event, after the surgical procedure has essentially beencompleted. At this stage, the intent is to close the trocar port toprevent any subsequent risk of herniation at the defect sites, a riskwith present suturing closure methods. Accordingly, since the trocarwill have already been removed along with the videoscope, and theabdominal cavity deflated, visibility and maneuverability within theabdominal cavity are necessarily severely restricted. This is incontrast to the significantly more accessible and visible situation atthis location during the surgical procedure itself.

Material of the Central Insertion Stem

In one or more embodiments, the central insertion stem 108 is made ofmaterial that is non-reactive but not itself biodegradable. The centralinsertion stem 108 can be discarded or reused, and may be made invarying lengths to enable surgeons in different situations dealing withpatients of different sizes to be able to control the placement of thebiodegradable wound closure device.

In one or more embodiments, the central insertion stem 108 is fabricatedof two polymers of differing grades—a short-term degradation material atthe protruding end, and a longer-term material at the location of theholding mechanism. Such a dual-material component might be readilyassembled using a mechanical or other joint type at the desired locationalong its length, where the two polymer grades intersect. Uponcompletion of the surgical procedure and implanting of the wound closuredevice, the protruding central insertion stem 108 can be cut off belowthe anterior surface of the subcutaneous layer but above the juncture ofthe two grades of polymer. With a short-term biodegradable material forthe anterior portion of the central insertion stem 108—well beyond thesuperfascial button 104 and its securing frictional or ratchetingfeature—the potential problem with stem removal is eliminated. To avoida possible mix-up during fabrication and assembly of such adual-material central insertion stem the different grades of polymercould be tinted different colors.

DESCRIPTION OF USE OF ONE OR MORE EMBODIMENTS OF THE INVENTION

One or more embodiments of the use of this invention are describedherein.

Connect the subfascial button 102 to the assembly consisting of thescrew 306 and superfascial button 104. In one or more embodiments, thesuperfascial button 104 could be a separate component which needs to beconnected to the screw 306. The central insertion stem 108 can then beconnected to the biodegradable wound closure device by threading it ontothe screw 110. In one or more embodiments, the superfascial button 104can be inserted over the central insertion stem 108 prior to attemptingto implant the wound closure device. In other embodiments, thesuperfascial button 104 can be inserted after the subfascial button 102is implanted. In other embodiments, the superfascial button 104 ispermanently attached to the screw 110, such that the superfascialbutton-screw assembly is threaded into the subfascial button 102, andthe central insertion stem 108 is threaded into a threaded hole in thesubfascial button 412.

Using the central insertion stem 108, guide the biodegradable woundclosure device to the wound site and press it through the site. Thenpull back on the central insertion stem 108 to cinch it in place. In oneor more embodiments, if not already done place the superfascial button104 on the central insertion stem 108, connector-side up and allow it toslide into position at the top of the subfascial button 104.

Once the biodegradable wound closure device is in place, place the outertube 106 over the central insertion stem 108 by sliding the outer tubeover the central insertion stem 108 through the hole in the outer tube408 and slide the outer tube 106 into place over the superfascial buttonconnector 602. FIG. 11 shows what the configuration would look like inone or more embodiments of the present invention.

Rotate the outer tube 106 until the outer tube protrusions 1006 line upwith the superfascial button connector 602. The outer tube 106 shoulddrop slightly so that the protrusions 1006 are inside the superfascialbutton connector 602.

Once the outer tube 106 is in place, it can be used to compress thebiodegradable wound device against the fascia and associated abdominallayers. While grasping the central insertion stem 108 with one hand.Rotate the outer tube 106 in the direction appropriate to the threads ofthe screw 110, until it feels tight. In one or more embodiments, thisdirection would be the opposite sense of the threads on the centralinsertion stem 904 to prevent it from slipping out. FIG. 12 shows theresulting configuration where the biodegradable wound device has beencompressed.

FIG. 13 shows an embodiment of the invention in place. As statedpreviously, the laparoscopic trocar is removed, leaving a residualdefect in the fascia-peritoneal layer 1306 under the skin 1302 whichgoes through the skin 1302 and intermediate tissue layers above thefascia 1306 and into the wound 1308, after the laproscopy tunnel andsurgical tools have been removed. The ability for the surgeon to seeinto the wound is impaired because there is nothing holding the sides ofthe wound up. The surgeon would hold the central insertion stem 108 tokeep the subfascial button 102 in place while applying a rotationalforce to the outer tube 106 over the screw 110 to move the superfascialbutton 104 toward the subfascial button 102. This results in compressingthe fascia between 1304 it.

FIG. 14 shows an embodiment of the invention after the central insertionstem 108 and outer tube 106 have been removed. The fascia 1304 iscompressed and pushed into the area under the superfascial button 104 bythe protrusions 414 on the subfascial button 102. The combination of thecompression and pushing mechanism acts to keep the device in place afterthe insertion process is complete.

FIG. 15 shows an embodiment of the invention during the healing process.The skin 1302 and fascia-peritoneal layer 1306 have healed over the areaof the tunnel and the wound 1308 is healing. The material of the screw110, subfascial button 102, and superfascial button 104 are still on thewound 1308 because of the initial compression and pushing of the tissue,but are degrading. By the time they degrade to the point where they nolonger provide any engagement with the fascia tissue 1304, the wound1308 will have healed sufficiently to complete the process.

Once the wound closure device has been compressed against the fascia asshown in FIG. 13, the outer tube 106 can be removed. FIG. 14 shows anembodiment of the wound closure device against the fascia wound 1308with the central stem removed. The wound closure device is left in placeby unscrewing the central insertion stem 108 from the subfascial buttonthreads 412. The wound can be closed at the epidermal layers. As shownin FIG. 15, the fascia wound 1308 will heal and the biodegradable woundclosure device will dissolve over time. In one or more embodiments, thebiodegradable wound closure device will be constructed of biodegradablepolymers of various expected degrading times, such that the parts of thewound closure device which are not required to hold the wound in placewill dissolve faster than the parts that are required to hold the woundin place.

What is claimed is:
 1. A biodegradable implantable device formaintaining the alignment of the edges of a trocar defect, the trocardefect having a defect diameter, the fascia and associated layers aroundthe trocar defect having a thickness, the device comprising: a firstbiodegradable base having a first base diameter substantially equal tothe defect diameter, the first biodegradable base having: a firstsurface, the first surface capable of substantially contacting theposterior wall of the trocar defect, a first threaded hole substantiallythrough the center extending inward from the first surface but not allthe way through the first biodegradable base, and a second threaded holeextending inward from the first threaded hole but not all the waythrough the first biodegradable base; a second biodegradable base havinga second base diameter, the second biodegradable base furthercomprising: a first surface with a protruding ring along its outer edge,where the inner diameter of the protruding ring is greater than thefirst base diameter, such that the first surface of the firstbiodegradable base fits inside the inner walls of the protruding ring ofthe second biodegradable base with sufficient gap to allow reliableengagement of the fascia and associated layers with the device; a secondsurface with a plurality of slots of such depth and width to allowengagement with a plurality of mating protrusions on an external tool,and an unthreaded hole substantially through the center of the firstsurface and the second surface, the diameter of the hole substantiallyequal to the diameter of the second threaded hole in the firstbiodegradable base, configured to allow a device with the diameter andthreading to mate with the second threaded hole in the firstbiodegradable base to pass through unobstructed; and a biodegradableconnector for connecting the first surface of the first biodegradablebase with the first surface of the second biodegradable base, thebiodegradable connector defined to compress the first biodegradable baseagainst the second biodegradable base using an external force, whereinthe length of the connector is sufficient to connect to the firstbiodegradable base and the second biodegradable base while allowingenough space to maintain a predefined gap substantially equal to thetissue thickness between the first surface of the biodegradable base andthe first surface of the second biodegradable base, and thebiodegradable connector having an unthreaded hole substantially throughthe middle of the same size and alignment as the unthreaded hole in thesecond biodegradable base, allowing a device with the diameter andthreading to mate with the second threaded hole in the firstbiodegradable base to pass through unobstructed, wherein thebiodegradable connector threads into the first threaded hole of thefirst biodegradable base, and the diameter of the first threaded hole ofthe first biodegradable base is greater than the diameter of the secondthreaded hole of the first biodegradable base.
 2. The biodegradableimplantable device in claim 1, wherein the biodegradable connector,first biodegradable base, and second biodegradable base are made frombiodegradable polymers of differing degradation rates so that thebiodegradable connector degrades faster than the first and secondbiodegradable bases.
 3. The biodegradable implantable device in claim 1,wherein the first biodegradable base is made of a shape-memorybiodegradable polymer, wherein it can be inserted with a smallercross-section than it assumes after a short exposure to bodytemperature, at which point it covers a larger cross-section of thetrocar defect.
 4. The biodegradable implantable device in claim 3,wherein the shape-memory biodegradable polymer is shaped like ateardrop, and expands to a disc-like shape against the trocar defectafter exposure to body temperature.
 5. The biodegradable implantabledevice in claim 1, wherein the biodegradable connector comprises ascrew, wherein the screw is attached to the first biodegradable base andthreads into the second biodegradable base.
 6. The biodegradableimplantable device in claim 5, wherein the first threaded hole threadsof the first biodegradable base are the opposite handedness of thesecond threaded hole of the first biodegradable base.
 7. Thebiodegradable implantable device in claim 6, further comprising abiodegradable cone, the biodegradable cone connected to the secondsurface of the first biodegradable base.
 8. The biodegradable device inclaim 7, wherein the first surface of the first biodegradable basefurther comprises a frictional control mechanism to prevent the fasciaand associated layers contacting the first surface from sliding orshifting laterally while in contact with the first surface.
 9. Thedevice in claim 8, wherein the biodegradable cone, first biodegradablebase, and second biodegradable base and biodegradable connector are madefrom biodegradable polymers of differing degradation rates so that thebiodegradable connector and biodegradable cone degrade faster than thefirst and second biodegradable bases.
 10. The biodegradable implantabledevice in claim 1, wherein the biodegradable connector comprises ascrew, wherein the screw is attached to the second biodegradable baseand threads into the first biodegradable base.
 11. The biodegradabledevice in claim 1, wherein the first surface of the first biodegradablebase further comprises a frictional control mechanism to prevent thefascia and associated layers contacting the first surface from slidingor shifting laterally while in contact with the first surface.
 12. Thebiodegradable device in claim 11, where the frictional control mechanismon the first surface of the first biodegradable base could be one of:small conical protrusions distributed radially on the first surface ofthe first biodegradable base, the vertex of the protrusions facing awayfrom the first surface, texturing the first surface, or leaving thefirst surface unpolished.
 13. The device in claim 11, wherein the firstbiodegradable base, and second biodegradable base and biodegradableconnector are made from biodegradable polymers of differing degradationrates so that the parts of the components used to implant thebiodegradable implantable device degrade faster than the parts of thecomponents used to compress the wound.
 14. The device in claim 11,wherein the second surface of the second biodegradable base furthercomprises ridges.
 15. The device in claim 11, wherein the second surfaceof the second biodegradable base further comprises a raised ring, suchthat the raised ring has notches to enable insertion of a tool to applya torque to the second biodegradable base.
 16. A biodegradableimplantable device for maintaining the alignment of the edges of atrocar defect, the trocar defect having a defect diameter, the fasciaand associated layers around the trocar defect having a thickness, thedevice comprising: a first biodegradable base having a first basediameter substantially equal to the defect diameter, the firstbiodegradable base having: a first surface, the first surface capable ofsubstantially contacting the posterior wall of the trocar defect, afirst hole substantially through the center extending inward from thefirst surface but not all the way through the first biodegradable base,and a second threaded hole extending inward from the first hole but notall the way through the first biodegradable base; a second biodegradablebase having a second base diameter, the second biodegradable basefurther comprising: a first surface with a protruding ring along itsouter edge, where the inner diameter of the protruding ring is greaterthan the first base diameter, such that the first surface of the firstbiodegradable base fits inside the inner walls of the protruding ring ofthe second biodegradable base with sufficient gap to allow reliableengagement of the fascia and associated layers with the device; a secondsurface with a plurality of slots of such depth and width to allowengagement with a plurality of mating protrusions on an external tool,and an unthreaded hole substantially through the center of the firstsurface and the second surface, the diameter of the hole substantiallyequal to the diameter of the second threaded hole in the firstbiodegradable base, configured to allow a device with the diameter andthreading to mate with the first hole in the first biodegradable base topass through unobstructed; and a biodegradable connector for connectingthe first surface of the first biodegradable base with the first surfaceof the second biodegradable base, the biodegradable connector defined tocompress the first biodegradable base against the second biodegradablebase using an external force, wherein the length of the connector issufficient to connect to the first biodegradable base and the secondbiodegradable base while allowing enough space to maintain a predefinedgap substantially equal to the tissue thickness between the firstsurface of the biodegradable base and the first surface of the secondbiodegradable base, and the biodegradable connector having an unthreadedhole substantially through the middle of the same size and alignment asthe unthreaded hole in the second biodegradable base, allowing a devicewith the diameter and threading to mate with the second threaded hole inthe first biodegradable base to pass through unobstructed.
 17. Thebiodegradable implantable device in claim 16, wherein the biodegradableconnector comprises a ratcheting mechanism.
 18. The biodegradableimplantable device in claim 16, wherein the biodegradable connectorcomprises a locking or clasping mechanism.